Oxygen generating canister



C. B. JACKSON ET AL OXYGEN GENERATING CANISTER Jan, 10, 1950 Filed Nov. 27, 1944 H mm 3% m may/5% D u m m M g M M a m wflw A 5 THE/Q a 7- TORNE KS.

Patented Jan. 10, 1950 2,494,131 oxxGENnENERATiNG oANI's'rEIt' Garey BsJack'son'; Wilkinsbur'g';

application-November z7, 1944, Serial"No565;39 2

4 Claims. 1.

This invention relates 'to oxygen-generatingapparatus and to containers-ion oxygen-liberating:

compositions.

It-has been proposed for -man-y years to use the alkali metal peroxides as-materials for producing 'substantiallyr'purefree oXyger-r.- One reasonf is that oxygen can be generatedrapidlyvandin large volume by the controlled;addition of 1 suitable reagents to :those peroxides, for. instance in an-apparatus ton-theprinciple of the Kippigen erator. Moreparticularly however, these peroxides reactpromptly and quantitatively.- 'with carbon-dioxide and moisture contained-in exhaled airto liberate oxygenand fix the carbon dioxide Wherefore they are particularly applicable to self contained breathing apparatus, such for example, as is used in non-respirable atmospheres and for high: altitude flying.

For such purposesthe alkali metal 5 peroxide;

whether pure sodium peroxide (NazOz) lpure pof tassiumtetiOXid (K204), or miXtl lisbf thl'll,

is packed 'in ca'nist'ers made from" sheet iron] or bla'ck plate,- and enerally simuann shape to those thathave been used "with gas masks 'loi" many years. They have proved to be satis'iac torily efiicient in performing their intende'dfun'ction, the oxygen reacting promptly with respired airto"maintain thepr'oper oxygen balancefeven at loiv'temperaturesl' xtended experience With" such canisters has shown,'however',' that the'great reactivity of'these peroxides makespos'sible the occurrence of serious and dangerous'acci'dent's: Thus, these per oxides react with explosive violence'vzitlisuch oxidizable materials as"lubri'catin}g "oil and 'gas'o line; It is easy enough toavoidtlie"'entry*of such materials into the'canister;"but there'ac tivity ofthe-peroxi'de's-is such'as equally tofcause spontaneous combustion of other combustible'or ganic materials such as paper, w'cod and rub ber, with therapitl liberation of large amounts of heat.-- In the produ'ction of such canisters on a large scale" it isvir'tiiallgr impossible to prevent a small piece of rubber, paper, Wood or similar organio'solid 'fr0m'fiiiding"its Way into an occasional canister; This is unimportant-as long as the canister remains sealed; but when:

it is placed in use the locally high concentration of oxygen causes thefor'ei'gn matter to begin to'be oxidized rapidly'with development of" (Cl. 23*281) V 2-.

canister meta-12" This has happened in a'ctual use of thesecanisters;- and 'itis gravely 'serious; not" only because theuser-Wears the canister so that his body is exposed to the molten'm'atter: which 5 pours-forth When" penetration takes-place; in

contact with his chest; but also bCau'S-Eflfi'efalk ing= of -molten iron and peroxide are 'potentially dangerous where -conibustible or explosive: mat=--" ter" is -in the immediatevicinity: Extensive de struct-ion of thecanister is"particularlv-likely if the-hot spot --develops in "contact"withor close to-'one=of theiron wire screens: that has beeri used in these canisters --topreVen-t channeling of the circulatin gases. v

It is amongthe objectsof "this invention to provide": alkali metal peroxide oxygen-liberating apparatus, such as breathing=-- apparatus canis ters; or oxygen- 'generators which +issimpler ef;- ficiently eliminates the danger-created -bythe presence ofsmall pieces-of wood and-otherworld- Joustible organiosolids -thatmay; be--present-in the peroxide; and whoseconstruction neithercomplicates ncr interferes withthe production of- 'the-containers-or their assembly witlrthe peroxide; 7 p

Another object is to f provide-a containerfor-- alkalimetal peroxides which renders harmless: thepresence of-a-small amount cfwvood-or other combustible organiomatter: y

A The invention will bedescribed fWi-th: reference;- to--the-accompanylng drawings 4 in WhihFlg;- "l"- is' a vertical elevationof a.;conventional type of breathing.- apparatus-=canister; parts being broken-" away, for purposes of illustration and Fig--2 a" cross section taken on line I III, Fig. 1.

The invention; -is-predicated--upon---our disc0very that the danger attendant upon- '-thepres-- once of a smallpiece of-wood-, .rubber, paper, or other combustible organic solid whenpresent contact with alkali metal peroxide in abreathiri "apparatus -canister or oxygen? generator can avt'ii'iiedfby' so "constructing-the canister r:

than 1r6r'i of" p N us'tio"n"' offisucli foreign" matter "occurs "the fh'a't' is" rapidlyfab"-'' sorbed bythatsurface and rapid carrie'deway" froiri the" zone-oi? reactionso that' the ter'ripra T1 tuie in tli" vicinity "of thebrgahiclriittf (as not become hig'h enough to *initia'te nieltin" "or burning-ofthcanistrl The meatwhich are suitable fdr 'the pu oses of the 'lI'ii fifildfihlilliOSe "Whi e al e hig P heat" conductive "and which do' notco ih d1- rectly with or do not burn readily in pi1rb--oxy-' en: Gold anu'sil'v'er mightbe used forthis perpos'e', and the thermal conductiV-ity of asmolybdenuni and tungsten-is sufficieritly for the purpose ofthe invention* if tne mass of high heat conductivity.

present is such as to-take up the amount of heat thatlmust be dissipated to prevent the formation of local hot spots in accordance with the invention. Those metals, are, however, expensive, and some of them constitute critical materials at the present time. For most, if not all, purposes we have found that copper is perfectly satisfactory from all standpoints, and is the metal best suited for the purposes of the invention. Its heat conductivity is high, sheet copper is readily formable, and we have found that it acts satisfactorily to completely avoid the danger noted above.

Although aluminum and magnesium are satisfactorily heat conductive, they are unsuited for this purpose because they oxidize so readily. In fact, magnesium can burn in ordinary air. The use of such metals would therefore add to the danger described.

The entire canister or other container might be constructed from copper or equivalent metal That is unnecessary, however, and from some standpoints might be undesirable. Thus, canisters made from sheet copper are not so strong mechanically as those made from ordinary black plate or other ferrous sheet, and to make them heavy enough to resist damage would make them unduly unexpensive. We have found, on the other hand, that entirely satisfactory results are to be had merely by inserting within the canisters as now made and used a liner of sheet copper which is of the same size as and extends completely around the wall of the container body.

This preferred embodiment of the invention is shown somewhat schematically in the drawings, which show a breathing apparatus canister of a form commonly used and made by the drawing of sheet iron to provide a body portion 1 which is integral with a base 2. After the canister has been filled with the peroxide material 3 a cap or closure member 4 is fastened in any suitable way to seal the canister, as by crimping the edges followed by soldering. In accordance with the invention there is disposed within the body of the canister prior to filling it a sheet 5 of pure copper which, as appears particularly from Fig. 2, extends entirely around the inside of the body I and with which the peroxide charge 3 is in contact.

The canisters and other types of containers may, of course, be formed in various other ways and take various other shapes or forms. Likewise, they may be provided with suitable inlet and outlet means, as for introducing a reagent or exhaled air and for withdrawing oxygen. Thus, the breathing apparatus canister shown in Fig. 1 is provided, as is customary in the canister art, with an inlet 6 for air that is to be treated, and with a member 1 for coupling the canister to a breathing facepiece and through which air is withdrawn after being regenerated by passing through the peroxide charge 3. Both the inlet 6 and the coupling outlet 1 are, as is customary, closed by suitable seals that are broken when the canister is to be put in use. Such details are well known or are mere design features, and they form no part of the present invention; therefore they do not require detailed illustration or further description.

We have found through numerous carefully conducted tests that canisters of the type shown in the drawings and described above act with complete efficiency to negative the danger potentially presented by the presence of a small amount of solid combustible organic matter that may find its way into the peroxide filling, and included in our investigation were tests that were much more severe than any condition that is likely to obtain except under the most unusual conditions. Many tests have demonstrated that the hot spot which has characteristically occurred in the use of canisters as made heretofore when such organic matter gets into the peroxide, and which causes destruction of the canister, is absent when such organic matter is present in canisters provided by this invention. The organic matter is oxidized as before, and at the same rate, but the heat of reaction is rapidly absorbed by and distributed uniformly throughout the heat conductive surface. When such combustion occurs the canister becomes uniformly warm to the touch throughout its body. Thus, to repeat, the heat is carried away from the zone of reaction at a rate such as to keep the temperature low enough to avoid undesired consequences.

Various modifications may, of course, be made. Thus, the heat conducting surface of this invention may be provided in other ways than by liners, as by plating or spraying copper or the like on the inner surface of the container, or by the use of copper clad metal. Similarly, added protection may be had by using screens of copper wire instead of iron wire screens.

According to the provisions of the patent statutes, we have explained the principle and mode of practicing our invention, and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. An oxygen-liberating canister comprising a metallic shell having an inner lining of sheet metal of high heat conductivity not combustible readily in pure oxygen, an alkali metal peroxide disposed therein, an inlet conduit positioned in one end of the shell, and an exhaust conduit positioned in the other end of said shell.

2. A canister according to claim 1, said shell being formed from ferrous metal.

3. A canister according to claim 1, said liner being formed from copper.

4. A canister according to claim 1, said shell being formed from ferrous metal, and said liner being formed from copper.

CAREY B. JACKSON. HORACE C. BEAHM. ALFRED C. VAN ANDEL.

REFERENCES CITED The following references are of record in the file of this patent.

UNITED STATES PATENTS Number Name Date 928,978 Jaubert Aug. 22, 1909 1,001,873 Mauran et al. Aug. 29, 1911 1,025,191 Jaubert May 7, 1912 1,412,790 Uehling Apr. 11, 1922 1,632,309 Nitardy June 14, 1927 1,817,857 Tragesei Aug. 4, 1931 1,852,786 Muller Apr. 5, 1932 2,004,243 Hloch June 11, 1935 2,398,830 Hamilton Apr. 23, 1946 

1. AN OXYGEN-LIBERATING CANISTER COMPRISING A METALLIC SHELL HAVING AN INNER LINING OF SHEET METAL OF HIGH HEAT CONDUCTIVITY NOT COMBUSTIBLE READILY IN PURE OXYGEN, AN ALKALI METAL PEROXIDE DISPOSED THEREIN, AN INLET CONDUIT POSITIONED IN 